Keycloak with krakend giving error 403 after correct login?

Question

Hi I am trying to make an authentication using Keycloak and Krakend, i can send my request, log in and then when i try to access the resource (using Insomnia) i get:

403 Forbidden: No body returned for response.

I don't know why this is its behaviour, please help!

This is my Krakend.json configuration file:

{
  "$schema": "https://www.krakend.io/schema/v3.json",
  "version": 3,
  "timeout": "10s",
  "name": "APIGateway",
  "port": 8402,
  "extra_config": {
    "security/cors": {
      "allow_origins": [
        "*"
      ],
      "allow_methods": [
        "GET",
        "POST",
        "PUT",
        "DELETE",
        "HEAD"
      ],
      "expose_headers": [
        "Content-Length",
        "Content-Type",
        "Authorization"
      ],
      "allow_headers": [
        "*"
      ],
      "allow_credentials": true,
      "debug": true
    }
  },
  "endpoints": [
    {
      "endpoint": "/go",
      "method": "GET",
      "output_encoding": "no-op",
      "extra_config": {
        "auth/validator": {
          "alg": "RS256",
          "roles": [
            "user",
            "admin"
          ],
          "jwk_url": "http://192.168.3.10:8403/auth/realms/pippo/protocol/openid-connect/certs",
          "disable_jwk_security": true
        }
      },
      "backend": [
        {
          "url_pattern": "/api",
          "host": [
            "http://192.168.3.10:8080"
          ]
        }
      ]
    }
  ]
}

In Keycloak i created my realm, user with credentials (using admin permissions) and client, i think it's correct because my login with access token works fine, after the login I got 403.

Here's my service written in go:

func JSONHandler(c *gin.Context) {
c.JSON(http.StatusOK, gin.H{"ciao": "ciao"})
}

func Init() {
    router := gin.Default()
    router.Use(middlewares.CORS())
    router.GET("/api", JSONHandler)
    err := router.Run(":8080")
    if err != nil {
        log.Fatal("Oh no")
    }
}

Answer 1

Modifying the field:

"$schema": "https://www.krakend.io/schema/v3.json"

to

 "$schema": "https://www.krakend.io/schema/v2.4.3.json"

solved my problem!